Bike Gremlin

A contradiction: bicycle that has some sentimental value to me (1996 steel MTB) is the bike I use when it snows.

I want to remove old paint and paint it, in order to make it last as long as possible. I will remove all the components, completely dissasemle it (will do the job in the spring). Planing to sand-blast the paint on the outside. There are three questions:

1) How to clean the frame from the inside, without damage it?

2) How to best protect the frame from the inside after cleaning it?

3) How to best protect the frame from the outside? Plastic, or some other paint? What is the most durable and salt resistant?

Aesthetics is not too important, but if possible, I'd like to get a Ferrari metallic red finish. Good at wrenching, decent at painting with spray paint. Prepared to leave the job to professionals if that's advised as smarter option.

Merco_61

Spray painting is very difficult to get durable without oven-curing the paint. Powdercoating is a much better option.


Rosso Corsa in a metallic finish will nearly always be blotchy when applied to small, round areas like a bicycle frame unless you are a professional who has painted slim tubes very many times.


Frame saver treatment will do much to preserve the inside of the frame, just get a kit and follow the directions after paint and before the buildup.

79pmooney

A really cheap and very home-doable approach is to brush on 2 part epoxy. That stuff has the wonderful characteristic of flowing as it sets up so very distinct brush marks disappear completely. Not the hardest pain but it is very chip resistant. Epoxy on bare metal works very well so no primer is needed.

Other pluses: the epoxy you do not mix up will probably last and be as good as new for the rest of your life. Do a thorough clean and a light sand and second coats go on just as durable as the first. (And you can repair chips, fill in holes you no longer want and bond on whatever you now want with any epoxy before painting.) Even very hard epoxies have a window before they are completely set up where sanding is easy so filling ships, then sanding to match the old paint is not hard. Mixed paint can go into the freezer to extend its life. Useful for small touch-ups. Caution - once the paint starts to set up, DO NOT touch it! Let imperfections stand and deal with after it sets up or sand it out 80% set up. In the early stages as it goes through its flow state, it will stick to anything you bring into contact. It won't be pretty!

You can also spray the stuff. If you do a pro job, the results will be about 25% better than a good brush job that anybody can do. Epoxy and the required (if you spray) lacquer thinner are very bad to breath and for the environment. I wouldn't count on a respirator. Doing it by hand, little thinner is needed and with a halfway decent supply of fresh air, not an issue.

I used this approach (brush) when I was riding salt roads in the winter. Worked really well.

Ben

Andrew R Stewart 

I'll second this. I've painted two frames with Sears marine deck paint using a brush. Both times I used the associated primer. Both times this was after sandblasting and a phosphate solution application. The first time the brush marks remained, the second time they almost completely flowed out. I found that the mix ratio and/or the temperature were important to get right. I did the second inside (it was winter) in a closed off room and cranked up the heat. I would not suggest doing this in a closed room though. The gallon of paint and primer (the activator was a pint IIRC) went around several riders over a few years. We would comment on our drab green bikes when we rode together. Andy.

fietsbob

the really good paint, is applied to the bottoms of steel ships (Ex Navy, now living in a fishing port town)

it is expensive but Applied on a bike you wont need much..


my father's 1953 AMC Nash , at the Factory, was immersed in a tank of rust inhibiting Primer.

once clean you may be able to get paint inside the tubes..

to let hot air out without having it bubble up thru the molten brass, making the joint defective,
there are small holes in the smaller tubes.. you have access to the inside of those tubes, there..

NB if you choose powder coat , they have to blast the surface clean, and have it Untouched
to have the powder coverage come out right..

fill threaded holes with sacrificial bolts . other places can be masked off.. you wont have to remove the old paint, yourself.




'/,

HillRider

+1. I wouldn't attempt to clean the inside of the tubes except perhaps to run a few rags through the accessible ones with a rod to remove any loose rust. Then treat them with Weigels Frame Saver (available at bike shops or internet order) or Amsoil HDMP (available at most NAPA auto parts stores).

jsdavis

I recently had a frame powder coated and the powder coat shop stripped the old paint for me. I only had to disassemble and clean all the grease out.

They don't use sand to remove the paint because it can damage the metal. I don't remember what they used, maybe baking soda or walnut shells or something along those lines.

It cost $100 for strip and powder coat for just the frame. Additional $25 if I had a fork. This was for a single color. Pearl, metallic, etc would be additional cost starting at $20.

I've had other items powder coated before, like steel cabinets and the worker said they could do it cheaper if I did not care too much about the color. For example I wanted black but did not care about what shade of black so they bundled my job with another job that specified a shade of black.

Bike Gremlin

I can get a new alu frame for about 50 euros.

Sand blasting costs around 10 euros here.

Powder coating costs roughly the same - 10 to 15 euros.

Didn't know sand blasting could damage a steel frame though. Sacrificial bolts is a great idea!

So in case of powder coating, I'd need to leave inside of the frame protection for last, if I got it right?
Special frame savers are not available where I live, while ordering from abroad would make it cost about 20 euros on top of the purchase price, so that's out of the question. Is there an alternative way to do it. Regular engine oil, or some other widely available household or machine product?

fietsbob

Boiled Linseed oil has been mentioned before as an alternative.

jsdavis

For powder coating you should leave the inside for the last step. The frame will be heated to about 200C so you don't want anything that could potentially come out in the oven because it will ruin the coating.

Sand blasting is a generic name when abrasives are blasted to remove paint. Specifically sand can cause damage like scratch or pitting. I do not remember the abrasive that was used to strip my frame. Sometimes the abrasive is baking soda/sodium bicarbonate or walnut shells. The idea is to use something that will remove the paint without damaging the material underneath. Sodium bicarbonate is more gentle than sand.

02Giant 

Media blasting is the generic term. There are a multitude of mediums available including sand.

TimothyH

Another vote for powder coating.

It is dirt cheap, durable and comes in a myriad of colors and effects.

https://www.bikeforums.net/general-cy...ated-bike.html


-Tim-

Merco_61

If frame saver isn't available, perhaps Dinol or Tectyl that the car restorers use can be found. Otherwise, boiled linseed oil works.